Low-protein (LP) diets improve nitrogen utilization efficiency and mitigate environmental pollution, however, excessive reductions in crude protein (CP) result in total nitrogen (TN) deficiency, thereby compromising growth performance. This study investigated the effects of replacing calcium hydrogen phosphate with diammonium phosphate (DP) in an LP diet on growth performance, carcass traits, meat quality, plasma biochemical parameters, hepatic nitrogen-metabolizing enzyme activities, and amino acid (AA) profiles in finishing pigs under TN restriction. Additionally, 15nitroge (15N)-isotope tracing was employed in suckling piglets to track ammonia nitrogen assimilation by analyzing 15N enrichment in plasma and hepatic AA following 15N-DP administration. Sixty-three barrows (Duroc × Landrace × Large White; initial BW: 74.3 ± 3.8 kg) were randomly allocated to one of three dietary treatments: a normal protein (NP) diet (CP 13.47%), a LP diet (CP 9.06%), or a LP (CP 10.47%) diet supplemented with 1.07% DP (LDP). All pigs had ad libitum access to feed and water for 51 d. The ratio of essential AA nitrogen to TN was 0.43, 0.50, and 0.43 in the NP, LP, and LDP diets, respectively. Pigs fed the LDP diet exhibited higher gain-to-feed (G:F) ratio (P = 0.014), plasma urea nitrogen concentrations (P = 0.001), hepatic non-essential amino acids (NEAA) concentrations (P = 0.028), and carbamoyl phosphate synthetase 1 (CPS-1) activity (P = 0.018), but lower average daily feed intake (ADFI, P < 0.001) compared with those fed the LP diet. The free AA profile of the longissimus dorsi muscle (LM) in pigs fed the LDP diet showed reduced concentrations of Arg and Phe (P < 0.05), but increased the concentration of Pro compared with those fed the NP diet (P = 0.037). To trace nitrogen fate, three suckling piglets received a 15N-DP-supplemented diet. 15Nitrogen enrichment in plasma and hepatic AA at multiple time points confirmed that dietary ammonia nitrogen was absorbed and incorporated into endogenous AA. In summary, dietary supplementation with DP in the LP diet improved nitrogen metabolism and AA synthesis, thereby enhancing G:F ratios without compromising carcass traits or meat quality. However, excessive DP supplementation may suppress feed intake, underscoring the need to optimize its dietary inclusion level to ensure efficient pig production.

Heat stress during summer significantly impairs seminal quality in swine production. As a key genetic resource for enhancing indigenous Chinese fatty pig breeds, Ningxiang boars require effective nutritional strategies to maintain reproductive performance under thermal challenge. This study aimed to investigate the effects of a combined antioxidant dietary supplement on seminal quality, antioxidant status, and gut microbiota in heat-stressed Ningxiang boars. Ten Ningxiang boars were randomly assigned to two groups (n = 5 per group). The control group received a basal diet, while the experimental group was fed the same basal diet supplemented with 400 mg/kg vitamin E, 5 g/kg yeast-derived zinc, 250 mg/kg yeast-derived selenium, and 800 mg/kg N-carbamylglutamate (NCG). Results demonstrated that sperm and seminal plasma superoxide dismutase (SOD) activity was significantly elevated in the supplemented group compared to the control (p < 0.05), whereas malondialdehyde (MDA) levels and total antioxidant capacity (T-AOC) did not differ significantly (p > 0.05). 16S rRNA gene sequencing revealed that dietary supplementation combined antioxidant markedly altered gut microbiota composition: the abundance of short-chain fatty acid-producing bacteria, particularly members of the Muribaculaceae family, increased significantly (p < 0.05), while opportunistic pathogens within the Acholeplasmataceae family were reduced (p < 0.05). These findings suggest that dietary supplementation with this antioxidant combination improves seminal quality in Ningxiang boars, potentially by enhancing endogenous antioxidant defenses and modulating gut microbial balance.

Weaning stress can severely damage the piglets' intestines. Microbial tryptophan catabolites play a vital role in maintaining the health of the intestinal mucosa. Indole-3-acetic acid (IAA), an indole derivative with known anti-inflammatory properties, has not yet been studied for its impact on piglets' intestinal health. Twenty-four weaned crossbred piglets (Duroc × Yorkshire × Landrace, weighing 6.58 ± 0.07 kg) were randomly allocated to receive diets containing 0, 120, or 240 mg/kg indole-3-acetate sodium (IAA-Na). Although dietary IAA-Na did not significantly impact growth performance or diarrhea incidence (P > 0.05), the 240 mg/kg IAA-Na elevated jejunal villus width (P < 0.05), tended to increase villus surface area (P < 0.10), and enhanced apparent nutrient digestibility alongside upregulating the mRNA expression of transporters (P < 0.05). Furthermore, dietary IAA-Na promoted intestinal epithelial cell proliferation and reduced secretory cell numbers (P < 0.05). Transcriptomic analysis of the jejunum of the 240 mg/kg group revealed significant modulation of pathways related to the "inflammatory response" and "immune system processes." Consistent with this, dietary supplementation with 240 mg/kg IAA-Na downregulated the content and expression of proinflammatory cytokines while upregulating the content and expression of anti-inflammatory cytokines in the jejunum. To further elucidate the effect of IAA on epithelial renewal, piglet jejunal organoids were employed as an in vitro model. Treatment with 0.5 and 2 μM IAA-Na significantly increased the organoids budding rate on d 3 (P < 0.01), indicating enhanced epithelial renewal capacity. In conclusion, although dietary IAA did not improve overall growth performance, 240 mg/kg IAA-Na promoted nutrient absorption in weaned piglets, potentially through enhancing anti-inflammatory responses and epithelial renewal.

Probiotics have been widely used for the regulation of intestinal health. Current screening methods for probiotics typically rely on animal or two-dimensional cell models. In this study, we employed intestinal organoids to identify a candidate probiotic strain. Furthermore, we investigated the potential mechanisms through which this strain and its active metabolites exert their effects, thereby evaluating the efficacy of this screening approach. Firstly, candidate probiotic strain PGM541 was identified from a porcine-derived Bacillus library by assessing organoid viability. Subsequently, to validate the organoid screening reliability, the potential mechanism of strain PGM541 on the intestinal epithelium was investigated; it was found to exhibit probiotic functions by regulating cell proliferation in both in vitro organoid and in vivo piglet models. Furthermore, organoid screening combined with metabolomic analysis identified butyric acid (BA) as the key bioactive metabolite responsible for driving epithelial proliferation. Whole-genome and transcriptomic analyses revealed the biosynthetic pathway of BA in strain PGM541. Importantly, BA receptor blockade experiments directly confirmed that BA enhances epithelial proliferation via interaction with the FFAR2 receptor, thereby validating its functional activity. Additionally, strain PGM541 exhibited protective effects against dextran sulfate sodium (DSS)-induced colitis, further validating the effectiveness of the intestinal organoid platform for probiotic screening. The probiotic strain PGM541, which was screened using intestinal organoids, promotes intestinal epithelial cell proliferation via its metabolite BA activating the FFAR2 receptor. These findings demonstrate that the intestinal organoid model serves as an effective platform for both preliminary probiotic screening and mechanistic investigation.

The purpose of this study was to explore the effects of changing standardized ileal digestible (SID) Lys levels in the diet on growth performance, carcass traits, meat quality, blood biochemical indices, and colonic volatile fatty acid levels of Ningxiang pigs, in order to determine their optimal SID Lys requirement. A total of 164 castrated Ningxiang pigs (days of age 135 ± 5and initial body weight of 35.57 ± 0.56 kg) were randomly divided into 5 dietary treatments with SID Lys levels of 0.50%, 0.60%, 0.70%, 0.80%, and 0.90%, respectively. Each treatment had 5 replicates with 6 to 7 pigs per replicate, and a feeding trial lasted for 45 d. Results showed that reducing dietary SID Lys from 0.50% to 0.90% did not affect final body weight (FBW), average daily gain (ADG), the ratio of feed to gain (F:G), and carcass traits (P > 0.05). The 0.50% Lys group exhibited a significantly higher proportion of n-3 polyunsaturated fatty acids (PUFA) and a lower n-6/n-3 PUFA ratio in the longissimus dorsi (P < 0.05), the proportion of saturated fatty acids (SFA) in the soleus was also higher compared with the 0.90% group (P = 0.038). In the 0.70% group, the levels of essential, non-essential, umami, and total amino acids in the longissimus dorsi were significantly increased (P < 0.05) while essential amino acid levels in the soleus were significantly higher in the 0.50% group. Additionally, blood urea nitrogen level was significantly reduced (P = 0.026) and colonic butyrate and total volatile fatty acid contents were significantly increased in the 0.50% group compared with the 0.70% group (P < 0.05). In conclusion, dietary SID Lys levels significantly influenced meat quality, blood biochemical indices, and colonic volatile fatty acids in Ningxiang pigs; however, reducing dietary SID Lys to 0.50% did not adversely affect their growth performance or economic traits.

The size of intestinal villi plays a critical role in determining digestive and absorptive functions, directly affecting nutrient digestibility and feed efficiency. Therefore, elucidating the key mechanisms regulating villus development is of significant importance. This study compares intestinal development in Shaziling pigs and Yorkshire pigs, which exhibit distinct lipid metabolism characteristics, revealing significant enrichment of different fatty acid metabolic pathways and the peroxisome proliferator-activated receptors (PPAR) signaling pathway. LC-MS metabolomics analysis further explores the potential correlation between changes in fatty acid metabolism and PPAR alpha expression, identifying glycerophospholipid metabolism and its key metabolite oleoylethanolamide (OEA) as critical factors. Pharmacological interventions and genetic mouse models manipulating PPAR alpha signaling demonstrate that OEA regulates stem cell activity and intestinal villus size via PPAR alpha, with this effect linked to energy metabolism driven by oxidative phosphorylation. Notably, dietary supplementation with OEA or palmitoylethanolamide-another endogenous PPAR alpha ligand increases villus size and nutrient digestibility. These findings indicate that lipid metabolism contributes to the regulation of intestinal villus size and uncover a novel mechanism by which N-acylethanolamines modulate intestinal morphological development through the PPAR alpha-oxidative phosphorylation axis. The results provide a theoretical basis for developing novel feed additives based on endogenous lipid signaling molecules.

The aim of our study was to evaluate the effect of dietary cobalt chloride (CoCl2) supplementation on diarrhea, growth performance, and intestinal development in post-weaning piglets. Twenty-six piglets weaned at 21 days of age (d 21) with similar body weights were randomly assigned to three treatments: a control group (n = 10), a low-dose CoCl2 group (1 mg/kg of diet; n = 8) and a high dose CoCl2 group (2 mg/kg of diet, n = 8). Piglets were housed individually and fed the experimental diets for 28 days, with a dietary transition at day 15. During the early post-weaning period (d0 to d14), dietary CoCl2 supplementation was associated with favorable trends in growth performance parameters, including ADG (average daily gain: linear, 0.05 < p < 0.1) and gain to feed ratio (linear, p < 0.05), as well as reduced fecal scores (Linear, p < 0.05). However, during the later post-weaning period (d15 to d28), increasing dietary CoCl2 levels were unfavorable trends in feed intake (Linear, p < 0.05) and ADG (Linear, 0.05 < p < 0.1). At the intestinal level, CoCl2 supplementation was associated with dose-related changes in intestinal morphology, epithelial cell differentiation, and luminal pH. Alterations were observed in duodenal crypt depth (CD) and ileal villus height (VH), and duodenal VH/CD (Linear, p < 0.05), without significant effects on ileal epithelial proliferation and apoptosis (p > 0.1). Changes in the numbers of goblet cells in villi (Quadratic, p < 0.05) and crypt (Linear, p < 0.05), and enteroendocrine cells (Quadratic, p < 0.05) in crypt exhibited dose-dependent trends. In addition, with the increase in the CoCl2 concentration, the expressions of genes related to nutrient transporters (DMT1, GLUT2, and SGLT1) and metabolism (HIF-1α, FBP1, and FBP2), as well as those related to the NOTCH signaling pathway (LGR5, ATOH1, HES1, and NOTCH2), showed a linear decrease (Liner, p < 0.05). This was the case except for LDHA and DLL4 (Liner, p < 0.05). The expression of the former was the lowest in the high-dose group, while that of the latter was the lowest in the low-dose group. In vitro, CoCl2 exposure was associated with reduced organoid budding rates (Quadratic, p < 0.01), the budding numbers (Linear, p < 0.05) per organoid, and altered gene expression of SGLT1 and CHGA (Linear, p < 0.05). In summary, dietary supplementation with CoCl2 exhibited dose- and time-dependent trends in weaned piglets. CoCl2 supplementation during the early post-weaning period (two weeks after weaning) was associated with favorable trends in growth performance and diarrhea, whereas prolonged supplementation (4 weeks after weaning) or higher dietary level (2 mg/kg of diet) were associated with unfavorable trends in growth performance and intestinal development. These findings suggest that CoCl2 may have potential as a short-term (two weeks after weaning), low-level (below 2 mg/kg diet) nutritional supplement, while caution is warranted regarding long-term supplementation or higher dietary inclusion levels.

This study evaluated the effects of replacing dietary glucose with fructose on intestinal development in weaned pigs and assessed epithelial growth using a small intestinal organoid model. A total of 26 weaned pigs ([Yorkshire × Landrace] × Duroc, 21 days old) were randomly assigned to three groups: a control group (10 pigs, 3% glucose), a low-fructose (LF) group (8 pigs, 1.5% glucose + 1.5% fructose), and a high-fructose (HF) group (8 pigs, 3% fructose), with one pig per pen. The experimental period lasted 28 d, including a dietary transition on day 15. Results showed that dietary fructose did not affect growth performance (P > 0.10). Fecal scores were not significantly different among treatments (0.05 < P < 0.1), although numerically lower values were observed in the LF group. The HF group had a greater relative length of the large intestine than the LF group (P < 0.05), whereas the LF group showed reduced kidney weight (P < 0.001). Regarding intestinal morphology, dietary fructose tended to reduce duodenal crypt depth and ileal villus height (0.05 < P < 0.1). Ileal malondialdehyde (MDA) levels were affected by dietary treatment (P < 0.05), whereas digestive enzyme activities were not altered (P > 0.10). At the molecular level, fructose significantly downregulated genes involved in carbohydrate metabolism (FBP1, FBP2, LDHA, PKM) and glucose transport (GLUT2) (P < 0.05). Stem cell-associated genes (LGR5 and BMI1) and tight junction-related genes (OCLN and CLDN1) were significantly downregulated (P < 0.05), whereas Ki67 expression was not significantly affected (P > 0.10). In organoid cultures, fructose concentrations did not affect budding efficiency (P > 0.10) but significantly affected the number of buds per organoid (P < 0.05), with higher values observed at 1 mM and 5 mM. Overall, replacing dietary glucose with fructose did not impair growth performance, but altered oxidative status, epithelial-related gene expression, and intestinal epithelial responses in weaned pigs. These findings indicate that intestinal responses are sensitive to dietary monosaccharide composition under practical feeding conditions.

The intestinal epithelium is particularly vulnerable to oxidative stress caused by intracavitary stimulation, but the molecular mechanisms driving this damage remain poorly understood. The arachidonic acid (AA) pathway was significantly enriched in the transcriptome of in vivo oxidative stress-induced jejunum and in vitro oxidative stress-induced intestinal organoids, highlighting its critical role in mediating oxidative stress-induced epithelial injury. Additionally, oxidative stress elevated levels of AA in the jejunum in vivo, while the expression of genes related to epithelial differentiation, nutrient digestion, absorption, and transport was downregulated both in vivo and in AA-treated organoids in vitro. These findings indicated that oxidative stress disrupts intestinal epithelial cell differentiation through AA, leading to impaired intestinal function. Notably, inhibiting AA release not only enhanced organoid viability under oxidative stress but also reduced inflammatory responses in mice exposed to oxidative stress, demonstrating that AA serves as a key effector molecule in mediating oxidative stress-induced intestinal injury. By employing organoid models, this study clarified the pathological involvement of AA in oxidative stress-related intestinal injury, offering novel perspectives for potential therapeutic interventions in oxidative stress-associated gastrointestinal disorders.

BackgroundThe objective of this study was to investigate the effect of L-tryptophan (L-Trp) and its metabolite kynurenine (Kyn) on the regulation of porcine intestinal epithelial cell proliferation.ResultsDietary supplementation of L-Trp significantly increased villus height and decreased crypt depth in the jejunum and ileum of weaned pigs. mRNA sequencing data and qPCR analysis found that L-Trp activated the expression of cell proliferative genes and the AHR (aryl hydrocarbon receptor)-MST1 (mammalian STE20-like kinase 1)-YAP1 (Yes-associated protein 1) axis in the ileum. Further in vitro analysis revealed that L-Trp treatment significantly enhanced cell proliferation of intestinal porcine epithelial cells-jejunum 2 (IPEC-J2) cells by activating the MST1-YAP1 signaling pathway. Further targeted metabolomics analysis identified Kyn as the core Trp metabolite involved in promoting IPEC-J2 cell proliferation. Mechanistically, Kyn interacted with AHR, which in turn bound to the upstream promote region of MST1 to initiate the transcription of downstream target gene YAP1 to activate intestinal epithelial cell proliferation. Furthermore, porcine intestinal organoid model also demonstrated that Kyn promoted intestinal organoid-budding efficiency and intestinal stem cell proliferation. Importantly, by using the AHR- or YAP1-specific inhibitors, the data confirmed that the Kyn-induced intestinal epithelial cell proliferation in IPEC-J2 cells and intestinal organoids was dependent on the activation of the AHR-MST1-YAP1 axis.ConclusionsTogether, this study has revealed a regulatory mechanism of Trp metabolism-derived Kyn in promoting porcine intestinal epithelial cell proliferation, offering insights into the connection between nutrient metabolism and intestinal epithelial homeostasis.

Iron deficiency is the most common comorbidity of inflammatory bowel disease (IBD), but the effect of iron supplementation on the repair processes of intestinal injury in weaned mice is unknown. This study aimed to evaluate the potential mechanism of dietary iron on intestinal injury and intestinal regeneration in the dextran sodium sulfate (DSS)-induced colitis of the weaned mouse model. The mice were fed either a control diet containing (45.00 mg/kg Fe) or iron supplemental (448.30 mg/kg Fe) diet for 14 days, followed by a 7-day oral administration of 2.5

Neonatal piglets possess lysosome-rich foetal-type enterocytes that facilitate uptake and intracellular processing of maternally provided nutrients. However, the role of lysosomes in early-life growth and intestinal maturation remains unclear. Therefore, this study was conducted to determine the role of lysosomes in the development of neonatal intestine in piglets. For 1-day-old neonatal piglets, a total of 12 piglets (Duroc × (Landrace × Large Yorkshire)) were divided into 2 groups using a split-litter design. To initiate malfunction in lysosomes, newborn piglets were subjected to oral gavage with imipramine (25 mg/kg bodyweight) once daily for 7 days. For 21-day-old piglets, a total of 12 piglets were divided into two groups, and each group received the same treatment as described above. Piglets receiving imipramine demonstrated significantly stunted growth at 7 days of age, but not at 27 days. By postnatal day 7, the foetal-type enterocytes of untreated piglets were restricted in the mid to upper ileal villus and contained several large lysosomal vacuoles. In contrast, marked changes in ileal morphological and histological structure were observed following imipramine treatment, as evidenced by reduced degree of vacuolation, decreased lysosomal count, as well as pronounced mitochondrial swelling; however, no vacuolated enterocytes were found in 27-day-old piglets. Furthermore, signaling pathways associated with lipid transport and metabolism were significantly enriched, and the related hub genes were identified by bioinformatic analysis after imipramine administration. These findings were further confirmed by biochemical analysis demonstrating that serum levels of total cholesterol (TC) and apolipoprotein A1 (ApoA1) were significantly increased while serum ApoB was decreased in 7-day-old piglets receiving imipramine treatment. Additionally, there was an opposite trend in levels of ApoA1and ApoB in ileal mucosa compared to serum. These results demonstrate that lysosome dysfunction induced by imipramine resulted in significant growth retardation, pronounced morphological and ultrastructural alterations in ileal enterocytes, along with disrupted lipid metabolism in early postnatal piglets; however, no such effect was observed in 27-day-old piglets. These findings enhance understanding of lysosomal functions and intestinal maturation in neonatal piglets.

Background: Microbial communities in the gastrointestinal tract play a critical role in nutrient absorption, metabolism, and overall health of animals. Understanding the structure and function of tissue-specific microbial communities in Ningxiang pigs is essential for optimizing their growth, development, and nutritional efficiency. However, the diversity and functional roles of microbiota in different nutrient absorption tissues remain underexplored. Methods: We collected samples from four key nutrient absorption tissues (NFC: Cecal Content, NFI: Ileal Content, NFL: Colonic Content, NFG: Gastric Content, N = 6) of Ningxiang pigs and performed 16S rRNA gene sequencing to analyze microbial community composition. Bioinformatics analyses included alpha and beta diversity assessments, linear discriminant analysis effect size (LEfSe) for biomarker identification, and PICRUSt2-based functional prediction. Comparative metabolic abundance analysis was conducted to explore functional differences among tissues. Results: Alpha diversity indices (ACE, Chao1, Simpson, and Shannon) revealed significant differences in microbial richness and evenness among the four tissues. At the phylum level, Firmicutes dominated the microbiota, while Bacteroidota was prominent in NFC and NFL. LEfSe analysis identified tissue-specific dominant microbial groups, such as f_Prevotellaceae in NFC, o_Lactobacillales in NFG, f_Clostridiaceae in NFI, and f_Muribaculaceae in NFL. Functional profiling using PICRUSt2 showed that the microbiota was primarily involved in organismal systems (e.g., aging, digestion), cellular processes (e.g., cell growth, transport), environmental information processing (e.g., signaling), genetic information processing (e.g., transcription, translation), and metabolic regulation (e.g., amino acid and carbohydrate metabolism). Comparative metabolic abundance analysis highlighted distinct functional profiles across tissues, with significant differences observed in pathways related to the immune system, energy metabolism, lipid metabolism, transcriptional and translational regulation, and aging. Conclusions: Our findings demonstrate that tissue-specific microbial communities in Ningxiang pigs exhibit distinct structural and functional characteristics, which are closely associated with nutrient absorption and metabolic regulation. These results provide valuable insights into the roles of microbiota in the growth and health of Ningxiang pigs and pave the way for future studies on microbe-mediated nutritional interventions.

The intestine is the largest immune and barrier organ in the body, and diarrhea and even death during piglet development are related to dysfunction caused by intestinal barrier damage and inflammation. A water-soluble β-glucan produced by Agrobacterium ZX09 has been shown to have a beneficial effect on gastrointestinal health. The main objective of this study was to investigate whether pre-feeding β-glucan has a protective effect on LPS-induced immune stress in piglets. In this study, 24 weaned piglets (21-day-old; 6.64 ± 0.16 kg) were assigned to 4 treatments in a two × two factorial design with diet (with or without β-glucan) and immunological challenge (saline or LPS). Piglets were challenged with saline or LPS after 39 days of feeding 0 or 200 mg/kg β-glucan. The results demonstrated that β-glucan supplementation increased the average daily weight gain and daily feed intake, and decreased diarrhea rate of piglets. Intestinal inflammation symptoms and histological changes in LPS-challenged piglets were alleviated by pre-feeding of β-glucan. β-glucan supplementation reduced serum IL-1β (interleukin-1β) and NO (nitric oxide) secretion in piglets after LPS challenge (0.01 < p < 0.05). Supplementation with β-glucan downregulated the mRNA expression of IL-6 in piglets after LPS challenge (0.01 < p < 0.05). β-glucan supplementation enriched the short-chain fatty acid-producing bacteria, such as Agathobacter and Subdoligranulum (0.01 < p < 0.05), and increased the concentrations of propionate and butyrate (0.01 < p < 0.05). In conclusion, pre-feeding β-glucan can enhance piglet immunity and promote piglet growth by influencing gut microbiota composition and metabolism, and alleviate intestinal damage after LPS challenge.

To find out whether dietary amylose/ amylopectin ratio (DAR) could attenuate injury in lipopolysaccharide (LPS)-challenged piglets, sixty male weaned piglets (Duroc × Landrace × Yorkshire, 21 days old, 6.51 ± 0.64 kg) were allotted to 5 dietary treatments with 12 cages per treatment, and fed ad libitum with diets different in DAR (0.00, 0.20, 0.40, 0.60 and 0.80). Feed transformation occurred from D15 to D21. On day 28, 12 h before slaughter, pigs were intraperitoneal injected with 100 μg/kg body weight LPS or sterile saline. Results showed that LPS stress caused an increase in serum urea nitrogen (UREA) and triglyceride (TG), but a decrease in alanine aminotransferase (ALT) activity and glucose (GLU) concentration (p < 0.05). Serum immunoglobulin G (IgG) concentration increased in DAR 0.80 but decreased in other groups after LPS stress (p < 0.05). Compared with the control group, concentrations of Ile, Leu, Phe, Val, Thr, Arg decreased in serum but increased in liver after LPS stress (p < 0.05). Serum Arg, Tyr, Sar, Ans, Orn increased linearly with increasing DAR (p < 0.05). Piglets in diet DAR 0.00 had highest superoxide dismutase (SOD1) and glutathione peroxidase 1 (GPX1) mRNA expression in liver than those in other groups (p < 0.05). There was significant effect of LPS stress * dietary DAR on total SOD activity and SOD1 mRNA gene expression (p < 0.05), LPS stress caused an increase in those two indices for pigs in groups 0.00 and 0.80. Piglets in diet 0.80 had the highest hepatic Cu, Fe, Mn, Zn concentrations than those in other groups (p < 0.05). Cecal indol(e) concentration was higher in diet 0.00 than that in diet 0.80 (p < 0.05). After LPS stress, colonic skatole concentration increased in DAR 0.40, 0.80 but decreased in other groups (p < 0.05). In conclusion, adverse effects of the LPS challenge could be reversed by feeding weaned piglets with low or high DAR diet through regulating amino metabolism and antioxidant function.

[This corrects the article DOI: 10.1016/j.aninu.2021.05.002.].

The ileum serves as the primary site for nutrient digestion and absorption in the intestine, with villus height representing a critical indicator of intestinal absorptive capacity. To investigate the regulatory mechanisms underlying ileal villus development, we conducted a feeding trial using crossbred pigs (Duroc × Landrace × Yorkshire) with an initial body weight of 27.74 ± 0.28 kg, stratifying them into high-villus and low-villus groups based on ileal villus height (n = 4). The results revealed 849 differentially RNA-edited genes (REGs) between the two groups, including 472 hyper-edited genes in the low-villus group and 377 in the high-villus group. Functional enrichment analysis showed that these REGs were significantly enriched in inflammation-related pathways, particularly the TNF signaling pathway and IL-17 signaling pathway, with TNF pathway genes exhibiting notably higher editing levels in the high-villus group. Additionally, 46 differentially expressed genes (DEGs) were identified, comprising 22 upregulated in the low-villus group and 24 in the high-villus group, which were similarly enriched in TNF and IL-17 signaling pathways. Integrated quadrant analysis of the RNA editing and transcriptomic profiles demonstrated that pro-inflammatory genes CXCL10 (C-X-C motif chemokine 10), CCL2 (C-C motif chemokine ligand 2), CREB3L2 (CAMP-responsive element-binding protein 3-like 2), and PIK3R1 (Phosphoinositide-3-kinase regulatory subunit 1) were highly expressed in the low-villus group but exhibited significantly lower RNA editing levels compared to the high-villus group. Furthermore, the expression of the inflammation-suppressive RNA editing enzyme APOBEC1 (apolipoprotein B mRNA editing enzyme catalytic subunit 1) showed correlation with villus height (R = 0.81, p < 0.05). Collectively, our findings indicate that RNA editing dynamics influence the variation in ileal villus height within inflammation-associated pathways, particularly the TNF signaling pathway. Enhanced RNA editing of this pathway may mitigate intestinal inflammation and promote healthy ileal villus developments.

Intestinal epithelial cells are the primary performers of intestinal functions and have a highly glycosylated surface. Membrane proteins are regulated by N-linked glycosylation, making it likely that glycosylation plays a key role in cell differentiation. To investigate the effect of glycosylation on intestinal morphology, we selected 90 pigs with an average initial body weight of 27.74 ± 0.28 kg to be housed for an experimental period of 100 d. Individuals with different villus heights were screened on the basis of duodenal intestinal morphometrics data and demonstrated that the apparent digestibility of amino acids in ileo-terminal chyme was positively correlated with villus height. The regulatory mechanism of intestinal villus height was then analyzed by transcriptomic sequencing and glycosylation proteomics, and it was found that this difference might be caused by the N-glycan biosynthesis pathway and different N-glycosylation processes on the cell surface. mRNA of genes related to the N-glycosylation synthesis pathway were more highly expressed in individuals with high villus height (P < 0.05), and the expression of genes targeting the Wnt signaling pathway was consistent with the trend of glycosylation-related genes, and the expression of its repressors was lower (P < 0.05). In order to verify the above results, 24 weaned piglets ((6.58 ± 0.15 kg) at 21 d of age) were randomly divided into 3 groups fed 0, 1, 3 g/kg N-acetyl-D-glucose, and 24 weaned piglets ((4.27 ± 0.13 kg) at 21 d of age) were randomly divided into 3 groups fed 0, 0.5, 1 g/kg fucose, then the samples were taken for testing after 28 d. The results showed that glycosylation processes occurring on the surface of duodenal intestinal epithelial cells can influence intestinal morphology through the Wnt signaling pathway.

Optimal dietary calcium (Ca) and phosphorus (P) requirements remain undetermined for Ningxiang pigs, a valuable indigenous Chinese breed. This study conducted a continuous feeding trial with two growth phases (grower: 30-50 kg; finisher: 50-80 kg) using fixed Ca/P ratios to systematically evaluate the effects of Ca/P levels on growth performance and mineral metabolism. A total of 180 pigs per phase were allocated to four Ca/P levels. During the grower phase, a dietary regimen of 0.83% Ca/0.67% P significantly increased the average daily feed intake (ADFI), average daily gain (ADG), and apparent total tract digestibility (ATTD) of energy and P. In the finisher phase, 0.60/0.48% Ca/P showed optimal growth performance, upregulated jejunal mineral transporters (CaSR and SLC34A2), enhanced bone mineralization (metatarsal ash content), and improved intestinal morphology (duodenal and jejunal villus height, jejunal villus surface area). This regimen also selectively enriched Peptostreptococcaceae abundance, indicating improved host-microbe interactions. Based on these findings, stage-specific nutritional strategies were recommended: 0.83% Ca/0.67% P during the grower phase and 0.60% Ca/0.48% P during the finisher phase. These protocols synergistically improve microbial ecology, intestinal function, and bone metabolism, thereby maximizing the growth potential of Ningxiang pigs.

ABSTRACT This study investigates the effects of different crude protein (CP) levels on growth performance, serum biochemistry, organ indices, intestinal morphology, colonic volatile fatty acids, and gut microbiota in Ningxiang finishing pigs. Ninety‐six pigs (53.20 ± 0.53 kg) were randomly assigned to three dietary treatments: high‐protein (HP, 15.56% CP), medium‐protein (MP, 12.94% CP), and low‐protein (LP, 10.31% CP), with four replicate pens per treatment and eight pigs per pen. Results showed that dietary CP levels had no significant effects on growth performance. However, the LP diet significantly reduced serum urea nitrogen, liver weight, and relative liver weight ( p < 0.05). Additionally, jejunal crypt depth showed a linear decrease in response to graded reductions in dietary CP levels (Linear, p < 0.05). The LP diet significantly decreased the contents of isobutyric, isovaleric, and branched‐chain fatty acids in colonic fermentation products ( p < 0.05). Furthermore, 16S rRNA sequencing revealed that the relative abundances of Terrisporobacter , Marvinbryantia , Turicibacter , Lachnospiraceae_AC2044_group , unclassified_f_Peptostreptococcaceae , norank_f_Eubacter_coprostanoligenes_group , Lachnospiraceae_UCG‐007 , and UCG‐009 were significantly higher in the LP group ( p < 0.05). Spearman correlation analysis indicated that isobutyric acid and isovaleric acid were negatively correlated with Lactobacillus and positively correlated with Streptococcus . In conclusion, the LP diet improved colonic microbiota composition while maintaining growth performance in Ningxiang finishing pigs. These results advance our understanding of protein nutrition in indigenous fat‐type pig breeds, providing a theoretical foundation for optimizing dietary formulations specifically in Ningxiang pigs.